Which of the following is a method to purify metals?

Hoope's process is a well-established method for purifying certain metals, particularly those that form volatile compounds when they react with chlorine. In this process, impure metal is subjected to a reaction with a chlorine gas, resulting in the formation of metal chlorides. These metal chlorides can then be easily separated by sublimation or distillation, allowing for the collection of pure metal as a residue after decomposition of the chloride.

While distillation is a technique used in chemistry for separating liquids based on boiling points, it is not a method specifically used for purifying metals in most cases. Filtration is a physical separation method useful for separating solids from liquids or gases, but it doesn't change the composition of the metal itself. Combustion refers to a chemical reaction where a substance reacts with oxygen to produce heat and light, which is not a method for purifying metals. Hoope's process uniquely leverages the reactivity of metals with chlorine for effective purification.